The instant invention relates to a novel process for preparing 2-diazo-3-trimethylsilyloxy-3-butenoates.
1-(4-Nitrobenzyl)-1-oxo-2-diazo-3-(trimethyl silyloxy) butene has been described (U.S. Pat. No. 4,525,582) as a synthon used in the conversion of 3-substituted-4-acetoxy azetidinones and penicillin to thienamycin.
A different process than this invention for preparing one of the silyloxy-3-butenoates, described as a key intermediate used in the synthesis of thienamycin and other carbapenem antibiotics, has been disclosed (U.S. Pat. No. 4,683,296) wherein a triflate silylating agent and a base were reacted with a p-nitrobenzyl diazoacetoacetate. This patent makes specific reference to the "use of weaker organic bases such as trialkylamines with the triorganic silyl halide silylating agent" which "does not produce the desired enol silyl ester" of this specific p-nitrobenzyl diazoacetoacetate.
The general reaction for converting simple nonfunctionalized ketones to silyl enol ethers has been previously described by Cazeau, et al. (Tetrahedron, 43, 2075-2088(1987)).
It is the object of the instant invention to provide a novel process for the preparation of diazosilyloxybutenoates which are useful in the synthesis of carbapenem antibiotic compounds.